In the past, there have been many different types of electrical boxes installed in concrete or cement (concrete and cement shall be used interchangeably herein). In general, the electrical boxes together with the electrical non-metallic tubing (ENT) connected thereto are oriented in the concrete form, together with the other elements, and concrete is poured onto the form embedding them therein.
In the past, electrical boxes have been supported in their final position on the form by tying to reinforcing bars (also referred to as rebars) prior to pouring the concrete form. However, instead of, or in addition to, steel rebars, post-tensioned cables or tendons have been used inside poured concrete to provide structural integrity to the concrete slab. Post-tensioned concrete slabs involve a series of cables or tendons which are tightened after pouring of the concrete. Compared to standard rebar reinforced concrete, post tensioned tendons or cables further increase the overall strength of the structure, which leads to a thinner concrete slab, reduced number of vertical support beams as well as quicker construction times. However, with fewer steel rebars in the concrete, as well as thinner concrete slabs, there are fewer elements within the form to which the electrical boxes can be tied in their final position.
Accordingly, one difficulty with the prior art process and system of tying electrical boxes to rebars is that additional time is required to perform this tying action, increasing the cost of installation. Furthermore, it is necessary to find rebar that is at the proper height and location and not being used for another purpose in order to tie the electrical box thereto. Furthermore, with post-tensioned concrete slabs, there are fewer rebars which can be used for tying the electrical box thereto.
Furthermore, with buildings having more glass exterior walls, there are fewer places to install an electrical receptacle in the wall. Therefore, building contractors and civil engineers have been installing the electrical receptacles in the floor. However, there are several difficulties with using floor boxes. For instance, if a typical concrete slab is 8″ thick with a further 2″ of flooring when installed, a typical floor box of only 6″ will be too short to fit within the typical concrete slab. Furthermore, most floor boxes currently offered in the marketplace have a flat bottom which typically rests on the surface area of the form which leaves an exposed area after the concrete has hardened and the form has been removed. This is undesirable because the exposed area must be patched requiring additional labour and increasing the construction times.
Furthermore, the electrical boxes have hubs that are used to receive the electrical tubing and conduit. These hubs may be generally located at the bottom of the electrical box. Because of this, if the box is resting on the concrete form, the electrical tubing must bend down to the hub of the electrical box. This can be difficult if obstacles, such as rebar and/or post-tension cables or tendons, are located close to an electrical box requiring the electrical tubing to be routed around such obstacles. Also, creating a bend in electrical tubing increases the difficulty to pull cable through the tubing after the concrete has been cured and could result in the electrical tubing being permanently and irrevocably damaged.
Accordingly, there is a need in the art for a system and device to maintain an electrical box at a final position on a form without tying the electrical boxes to elements, such as reinforcing bars contained within the concrete form. Furthermore, there is a need in the art to maintain the hubs of the electrical boxes at different distances from the concrete form in order to avoid excessive bending of the electrical tubing down to the hub and/or around other obstacles and elements also contained in the concrete form to reach the hub. There is also a need in the art for a robust system and method to accommodate concrete slab and floor thicknesses which may vary depending on construction methods used, such as whether or not post-tensioned slabs are used.